Rashi: It illuminates and increases after dawn.

Malbim: Derech is a great road. Orchos are small paths ¹ that branch off from the Derech to villages and to the side. Even though it seems that Tzadikim do not go on a wide path, for their path is full of thorns and it is hard to go on it, even though initially it is thorns, its end is flat. The narrow path on which they go, initially it seems like the light that begins to shine at dawn. It is not the sun's own light. Rather, it is sparks of the sun via vapors. Afterwards, it becomes the sun's own light, and increases constantly. So light of the Nefesh, initially it is covered with clouds of the body. Light of the sun is covered and hidden, and it breaks through bodily clouds and darkness of physicality. It becomes a bright light through the polishing (refinement) of the Nefesh.

Rashi: It is midday, the clarity of the day.